bug with order-only prerequisites implicit rules implementation ?
Greetings -
Please could anyone explain the behaviour of this test makefile (attached) :
quotecode
TMP:=/tmp
%.ext:
touch $@
.PHONY: *.oop
%.oop:
@echo 'A phony order-only prequisite of /tmp/a.t';
#$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext | %.oop
@echo Specific Rule
%.t:%.ext
@echo General rule
/code/quote
when invoked with :
$ make -f ${the_makefile} /tmp/a.t
I would expect that the most specific matching first rule
would be invoked always, with its extra order-only
pre-requisite recipe always being invoked, but actually
this occurs only if /tmp/a.ext does not already exist -
I tested latest make-4.1, and make-3.82, on a RHEL6 linux
platform, and both show the same behaviour:
$ make -f ${the_makefile} /tmp/a.t
touch /tmp/a.ext
A phony order-only prequisite of /tmp/a.t
Specific Rule
rm /tmp/a.ext
but if I :
$ touch /tmp/a.ext
and then :
$ make -f ${the_makefile} /tmp/a.t
Gemeral Rule
If I remove the phony order only dependency. so that the /tmp/%.t rule reads:
quotecode
$(TMP)/%.t:$(TMP)/%.ext
/code/quote
then the makefile always runs the first recipe, regardless of the existence
of /tmp/a.ext :
$ make -f ${the_makefile} /tmp/a.t
Specific Rule
$ touch /tmp/a.ext
$ make -f ${the_makefile} /tmp/a.t
Specific Rule
$ rm /tmp/a.ext
$ make -f ${the_makefile} /tmp/a.t
touch /tmp/a.ext
Specific Rule
rm /tmp/a.ext
Also, a second problem is that order-only dependencies are not
recognized when specified by multiple rules without recipes are
specified for same target , ie:
quotecode
$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext
/quote/code
has the same effect (recipe for implicit order-only pre-requisite never runs)
as no order-only dependency being specified at all. I thought the
dependencies should be merged and the %.oop recipe should be run in
this case, especially as I've told make that all *.oop targets are
phony.
Is this a bug with make ?
Any responses much appreciated.
Thank You Regards,
Jason Vas Dias
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bug with order-only prerequisites implicit rules implementation ?
Greetings -
Please could anyone explain the behaviour of this test makefile (attached) :
quotecode
TMP:=/tmp
%.ext:
touch $@
.PHONY: *.oop
%.oop:
@echo 'A phony order-only prequisite of /tmp/a.t';
#$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext | %.oop
@echo Specific Rule
%.t:%.ext
@echo General rule
/code/quote
when invoked with :
$ make -f ${the_makefile} /tmp/a.t
I would expect that the most specific matching first rule
would be invoked always, with its extra order-only
pre-requisite recipe always being invoked, but actually
this occurs only if /tmp/a.ext does not already exist -
I tested latest make-4.1, and make-3.82, on a RHEL6 linux
platform, and both show the same behaviour:
$ make -f ${the_makefile} /tmp/a.t
touch /tmp/a.ext
A phony order-only prequisite of /tmp/a.t
Specific Rule
rm /tmp/a.ext
but if I :
$ touch /tmp/a.ext
and then :
$ make -f ${the_makefile} /tmp/a.t
Gemeral Rule
If I remove the phony order only dependency. so that the /tmp/%.t rule reads:
quotecode
$(TMP)/%.t:$(TMP)/%.ext
/code/quote
then the makefile always runs the first recipe, regardless of the existence
of /tmp/a.ext :
$ make -f ${the_makefile} /tmp/a.t
Specific Rule
$ touch /tmp/a.ext
$ make -f ${the_makefile} /tmp/a.t
Specific Rule
$ rm /tmp/a.ext
$ make -f ${the_makefile} /tmp/a.t
touch /tmp/a.ext
Specific Rule
rm /tmp/a.ext
Also, a second problem is that order-only dependencies are not
recognized when specified by multiple rules without recipes are
specified for same target , ie:
quotecode
$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext
/quote/code
has the same effect (recipe for implicit order-only pre-requisite never runs)
as no order-only dependency being specified at all. I thought the
dependencies should be merged and the %.oop recipe should be run in
this case, especially as I've told make that all *.oop targets are
phony.
Is this a bug with make ?
Any responses much appreciated.
Thank You Regards,
Jason Vas Dias
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Re: bug with order-only prerequisites implicit rules implementation ?
On Sat, Jan 10, 2015 at 7:06 PM, Jason Vas Dias
jason.vas.d...@gmail.com wrote:
Please could anyone explain the behaviour of this test makefile (attached) :
quotecode
TMP:=/tmp
%.ext:
touch $@
.PHONY: *.oop
%.oop:
@echo 'A phony order-only prequisite of /tmp/a.t';
#$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext | %.oop
@echo Specific Rule
%.t:%.ext
@echo General rule
/code/quote
when invoked with :
$ make -f ${the_makefile} /tmp/a.t
I would expect that the most specific matching first rule
would be invoked always, with its extra order-only
pre-requisite recipe always being invoked, but actually
this occurs only if /tmp/a.ext does not already exist -
I tested latest make-4.1, and make-3.82, on a RHEL6 linux
platform, and both show the same behaviour:
$ make -f ${the_makefile} /tmp/a.t
touch /tmp/a.ext
A phony order-only prequisite of /tmp/a.t
Specific Rule
rm /tmp/a.ext
but if I :
$ touch /tmp/a.ext
and then :
$ make -f ${the_makefile} /tmp/a.t
Gemeral Rule
This behavior is documented. To quote from the info pages, section
10.5.4 How Patterns Match:
A pattern rule can be used to build a given file only if there is a
target pattern that matches the file name, _and_ all prerequisites in
that rule either exist or can be built. The rules you write take
precedence over those that are built in. Note however, that a rule
whose prerequisites actually exist or are mentioned always takes
priority over a rule with prerequisites that must be made by chaining
other implicit rules.
When /tmp/a.ext exists but a.oop doesn't, then the 'general' rule has
precedence because all the prerequisites exist, while the 'specific'
rule has a non-existent prerequisite (a.oop).
If I remove the phony order only dependency. so that the /tmp/%.t rule reads:
quotecode
$(TMP)/%.t:$(TMP)/%.ext
/code/quote
then the makefile always runs the first recipe, regardless of the existence
of /tmp/a.ext :
Given the explanation above, that should make sense.
Also, a second problem is that order-only dependencies are not
recognized when specified by multiple rules without recipes are
specified for same target , ie:
quotecode
$(TMP)/%.t: | %.oop
$(TMP)/%.t:$(TMP)/%.ext
/quote/code
has the same effect (recipe for implicit order-only pre-requisite never runs)
as no order-only dependency being specified at all. I thought the
dependencies should be merged and the %.oop recipe should be run in
this case, especially as I've told make that all *.oop targets are
phony.
Pattern rules, unlike normal rules, are never merged. Each one stands
alone and either completely overrides a previous pattern rule with the
exact same target and prerequisites (but possibly different commands,
or *no* commands, which cancels the previous pattern rule), or adds a
new pattern for the target with different prerequisites.
Philip Guenther
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